opt_if_simplification.rar_out

/* * Copyright © 2010 Intel Corporation * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. */ /** * \file opt_if_simplification.cpp * * Moves constant branches of if statements out to the surrounding * instruction stream. */ #include "ir.h" namespace { class ir_if_simplification_visitor : public ir_hierarchical_visitor { public: ir_if_simplification_visitor() { this->made_progress = false; } ir_visitor_status visit_leave(ir_if *); ir_visitor_status visit_enter(ir_assignment *); bool made_progress; }; } /* unnamed namespace */ /* We only care about the top level "if" instructions, so don't * descend into expressions. */ ir_visitor_status ir_if_simplification_visitor::visit_enter(ir_assignment *ir) { (void) ir; return visit_continue_with_parent; } bool do_if_simplification(exec_list *instructions) { ir_if_simplification_visitor v; v.run(instructions); return v.made_progress; } ir_visitor_status ir_if_simplification_visitor::visit_leave(ir_if *ir) { /* If the if statement has nothing on either side, remove it. */ if (ir->then_instructions.is_empty() && ir->else_instructions.is_empty()) { ir->remove(); this->made_progress = true; return visit_continue; } /* FINISHME: Ideally there would be a way to note that the condition results * FINISHME: in a constant before processing both of the other subtrees. * FINISHME: This can probably be done with some flags, but it would take * FINISHME: some work to get right. */ ir_constant *condition_constant = ir->condition->constant_expression_value(); if (condition_constant) { /* Move the contents of the one branch of the conditional * that matters out. */ if (condition_constant->value.b[0]) { foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) { ir_instruction *then_ir = (ir_instruction *)then_iter.get(); ir->insert_before(then_ir); } } else { foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) { ir_instruction *else_ir = (ir_instruction *)else_iter.get(); ir->insert_before(else_ir); } } ir->remove(); this->made_progress = true; } return visit_continue; }